1. Field of the Invention
The invention relates to a piezoelectric/electrostrictive ceramic composition and a piezoelectric/electrostrictive device using the piezoelectric/electrostrictive ceramic composition.
2. Description of the Background Art
A piezoelectric/electrostrictive actuator has an advantage of being able to precisely control a displacement in sub-micron order. Particularly, a piezoelectric/electrostrictive actuator using a sintered body of a piezoelectric/electrostrictive ceramic composition as a piezoelectric/electrostrictive body can precisely control a displacement and additionally has advantages of high electric-mechanical conversion efficiency, high motive power, fast response speed, high durability, and low electric power consumption and using these advantages, the actuator is used for heads of ink jet printers, injectors of diesel engines, and the like.
As a piezoelectric/electrostrictive ceramic composition for piezoelectric/electrostrictive actuators, conventionally Pb(Zr,Ti)O3 (PZT)-type piezoelectric/electrostrictive ceramic compositions have been employed; however the effect of the elution of lead from sintered bodies on the global environments has become a serious concern and since then, (Li, Na, K)(Nb, Ta)O3 type piezoelectric/electrostrictive ceramic composition has been investigated.
Further, as Japanese Patent Application Laid-Open (JP-A) No. 2003-206179 and JP-A No. 2004-244299 disclose, (Li, Na, K)(Nb, Ta, Sb)O3 type piezoelectric/electrostrictive ceramic compositions has also been investigated containing Sb as the B site element for improving the piezoelectric/electrostrictive properties.
Furthermore, International Publication No. 2006/095716 discloses that the piezoelectric/electrostrictive properties can be improved by the excess number of atoms of the A site element over that of the B site element in (Li, Na, K)(Nb, Ta, Sb)O3 type piezoelectric/electrostrictive ceramic compositions.
However, the conventional (Li, Na, K)(Nb, Ta, Sb)O3 type piezoelectric/electrostrictive ceramic compositions have problems that electric field-induced strain under high electric field application is not always sufficient, which is important as piezoelectric/electrostrictive actuators.